You fuck a female up the ass with a giant dildo. The ass is spread so as to create a crater like formation. This allows for the male to squirt his stuff, thus creating a pool of semen in the female's anus. The surrounding fecal matter of the asshole breaks off into the ejaculate goo, thus creating poop floaties.

Dude, did you hear? Tony walked in on his mother getting a Milky Way from her boyfriend.

The act of a female rubbing hot, melted chocolate over a mans penis. She then continues by giving the man a regular blow job from where the man ejaculates and mixes in with the chocolate creating a "milkyway". (The milky way is a spreading paste use for multiple activities eg. on bread, that consists of white and dark chocolate)The female can then continue licking the penis where she gets a mixture of both cum and chocolate.

That chick over there gives the best Milkyway's.
HOLY CRAP, that school girl on the corner is handing out FREE milkyways!

The act of filling a naughty bits orifice (usually vaginal or anal) with milk or a milk-like substance with a similar viscosity and then expelling it in a spectacular explosion, causing one or both participants to become awashed in a "milky way" or manner.

Dude, I went to this porn site and downloaded this brunette getting a milky way from a hot blond Hungarian chick!

Milkway or milkywaying as it is known is the act of pouring luke warm milk from fine bone china and only fine bone china into a womens particulary loose vagina, im talking like throwin a hot dog down an alleyway loose, and then proceeding to either fist, foot or stump pile drive her causing the milk to squirt out in the form of the milkyway galaxy. CAUTION ENSURE LUBRICATION OF THE FIST BEFORE INSERTING AS CASES OF HANDS GETTING STUCK AND THE FIRE BRIGADE BEING CALLED HAVE BEEN KNOWN TO OCCUR.

Man: Oh Edgar such a lovely night, perfect for a bit of milkyway wouldn't you say darlin.

I jerked myself off as she floated away from me. She was panting and had a mischievous look in her eye. With a groan, I shot my load across the distance, the pearly cum wobbling through recycled air. It reminded me of the milky way, in the second before it hit her in her flushed, grinning face.